1. Field of the Invention
The present invention concerns methods and compositions for delivering active pharmaceutical and imaging nanoparticles to a subject in need thereof.
2. Brief Description of the Related Art
Treatment and diagnosis of injuries and infections to vascular tissues is often problematic and the result of difficulties in administering the proper treatment to the site of such injuries or infections. These difficulties have prevented the development of effective treatments for these particular diseases and conditions, examples of which follow. For example, infection with hemorrhagic fever viruses presents a critical challenge to medicine because, among other things, of the severe and frequently fatal consequences of contagion (Borio et. al., JAMA 287, 1-51 (2002)). Hemorrhagic fever is caused by a diverse group of viruses that exert highly varied pathological effects. However, there are two common steps (one early, one late) in the pathogenesis mechanisms of these viruses. First, the preponderance of evidence suggests that infection of macrophages (monocytes), as components of the innate immune system, plays an important initial role in the propagation of the hemorrhagic fever viruses. Secondly, infection by hemorrhagic viruses results in bleeding, and in many instances the wound site is the result of viral damage to vascular cells.
The hemorrhagic fever viruses are members of the Filoviridae, Arenaviridae, Bunyaviridae and Flaviviridae families and have a genome that consists of a single strand of RNA. In general, the viruses work through the following mechanisms: (1) Thrombocytopenia—a reduction in platelet levels is a near-universal consequence of hemorrhagic fever virus infection; (2) Thrombasthenia—The thrombocytopenic condition in hemorrhagic fever can be exacerbated by platelet dysfunctions; (3) Reduced humoral coagulation factor concentrations—decreases in circulating levels of humoral coagulation factors can result from consumption (along with platelets at wound sites or with DIC) and/or damage to hepatic tissue for reduced factor synthesis; and (4) loss of vascular integrity—a loss in endothelial integrity, leading to plasma leakage and the formation of microvascular wound sites, is a common feature in hemorrhagic fever diseases. As a consequence, the pharmaceutical options for treating these viruses is limited.
Ribavirin is a nucleoside analogue that was first reported in 1972 to have broad-spectrum antiviral activities. While ribavirin (monophosphate) has been shown to inhibit inosine monophosphate dehydrogenase for a reduction in cellular GTP, more recent investigations indicate that this nucleoside analogue functions by increasing the intrinsic mutation rate of viruses for “lethal mutagenesis”. In tissue culture ribavirin has antiviral activities against a wide variety of viruses, including Flaviviruses, Arenaviruses, and Bunyaviruses. More significantly, ribavirin has been approved by the FDA for the treatment of the Flaviviridae family member hepatitis C virus, and has shown efficacy in the treatment of a limited number of patients with Arenavirus infections.
On the other hand, enthusiasm for ribavirin as an antiviral agent is diminished by three observations. First, promise based on the in vivo performance of ribavirin has not been fully realized in the clinic. For example, ribavirin has been reported to be ineffective in the treatment of infection from members of the Filoviridae and Flaviviridae families (Borio et al., supra). Secondly, this nucleoside analogue has been shown to limit hepatic tissue damage in patients infected with hepatitis C virus, but to require a dual therapy with interferon for viral clearance. Finally, a side effect of ribavirin chemotherapy is the induction of anemia as a result of red blood cell penetration and lyses. Accordingly, there is a need for new ways to administer ribavirin and other such active agents.
Another example is diagnosis of traumatic injuries. An accurate assessment of tissue damage is of paramount importance in the management of traumatic injuries. A key element in this assessment, particularly in patients with unstable or marginally stable hemodynamics, is a determination of the location of sites of internal hemorrhage. Physical examination, traditional X-ray angiography of contrast agents and CT localization of extravascular contrast agent can be used to localize sites of active bleeding. Radiological methods based on labeled red blood cells are useful, but frequently fail to detect bleeding sites. These techniques can be effective, particularly when used together. However, vasospasm and vaso-occlusion, as well as co-localization of several bleeding sites can result in a failure to identify hemorrhage sites. Also, the density of the contrast agent can occlude smaller sites of hemorrhage. This latter problem has been partially ameliorated by using less x-ray dense CO2 contrasting agent. The application of MRI methods developed for detecting vascular defects in hemorrhagic transformation holds promise as tools for localizing wound sites in some types of injuries, including brain trauma and spinal cord injury. However, a fundamental problem with the above methods is that imaging is based on the movement of vascular contents out of the circulatory system, and not directly imaging the actual angiopathic site of vascular breach.
Another example is treatment of cancers, such as prostate cancer. Prostate cancer remains a major cause of morbidity and mortality in middle-aged and older American men. Although several histological types of prostate cancer can be seen following biopsy, the vast majority of prostate cancers are adenocarcinomas of glandular origin. Advarices in diagnosis have resulted in approximately 90 percent of all prostate cancers being found either within the prostate or nearby. For the 90% of cases detected relatively early, the five-year survival rate approaches 100%. In contrast, the 10% representing disseminated disease experiences a five-year survival rate of only 34%. Only skin cancer and the combined mortality of the four common histological types of lung cancer are more common among this population. In 2007, the American Cancer Society anticipates clinical presentation of 218,890 new cases, with primary causation of approximately 27,050 deaths. A remarkable one in six American men will at sometime develop prostate cancer, with one in 34 succumbing to the malignancy.
A brief survey of the potential serious adverse events associated with current standard-of-care therapies illustrates the desirability of less invasive, more carefully targeted, tumor-specific diagnostic and treatment methods. It would be desirable to minimize the damage to healthy prostate, nerve and other extra-prostatic tissues while retaining or enhancing tumor killing efficacy as compared with current standard-of-care surgery or radiation. The serious adverse events which can be associated with prostate cancer surgery (open radical retropubic prostatectomy, open radical perineal prostatectomy, laparoscopic radical prostatectomy or transurethral resection of the prostate) include impotency, incontinence and post-operative infection. The impotency rate after radiation is the same as that of surgery with more than seven out of ten men becoming impotent within five years of having external beam radiation therapy. Although incontinence is less common than after surgery, the risk of incontinence increases every year after radiation until by six years after treatment, the rate is almost as high as that associated with surgery. Androgen ablation remains the standard therapy with advanced prostate cancer and causes disease remission in most men. However, the cancer eventually recurs and thereafter the median survival of patients is less than one year. The results of the proposed program for the development of nanoparticles-loaded platelets for directed energy transfer hold promise for ameliorating many of these difficulties. There is a critical need to improve current standard-of-care in prostate cancer, and the present invention may be an answer to that need.
Another example is treatment of cardiovascular disease and its related vascular pathologies. The unmet nature of the need for therapeutics for cardiovascular disease is evidenced by the expenditures in excess of $300 billion per year for the over 60 million patients in the United States with diagnosed disorders of the cardiovascular system. Most cardiovascular disease is caused by the concerted dysfunction of thrombotic, inflammatory and proliferative processes at sites of vascular injury. For example, acute myocardial infarction is the result of thrombotic occlusion of the coronary circulation that occurs when inflammatory and proliferative processes result in atherosclerotic plaque rupture. Similarly, restenosis after angioplasty and cardiac bypass is the result of initially thrombotic, then inflammatory and proliferative processes at the original vascular injury sites of the procedures. Increased understanding of the molecular mechanisms underlying thrombogenic, inflammatory and atherogenic processes in cardiovascular disease has resulted in numerous strategies for gene therapeutic intervention, including interfering with intracellular signaling and cell cycle control, amplifying antithrombotic intracellular signaling, inhibiting pro-atherogenic lipid metabolism. Several methods are currently employed to obtain site-specific gene delivery for cardiovascular gene therapy, including physical targeting with catheter-mediated gene transfer and direct needle injection into adventitia. Additional levels of specificity are obtained by employing tissue-specific promoters (e.g., SM22 for smooth muscle cell delivery). However, further tools for specific delivery of therapeutic compounds to the sites of injuries, including vascular injuries, would be desirable.
Blood platelets are a component of the circulatory and blood systems in the body, and are well-known in the art. U.S. Patent Application Publications 2005/0025748 and 2005/0272161 disclose fixed-dried blood cells and fixed-dried blood platelets that carry an active agent and that are useful to deliver active agents to a site of interest. The blood cells and blood platelets in these applications are “fixed” by chemical treatment with at least one chemical compound that is incorporated into at least a portion of the cells to structurally stabilize and/or extend the shelf-life of the cells. Disclosed fixing agents include formaldehyde, paraformaldehyde and glutaraldehyde, as well as permanganate solutions. However, it would be desirable to eliminate the fixation step in order to more rapidly and cleanly process blood platelets that carry desired agents.